Light emitting device and method for manufacturing a light emitting device

Abstract

A light emitting device comprising a substrate ( 6 ) having an electrically conducting circuit layer ( 8 ), a LED package ( 7 ) surface mounted on the substrate ( 6 ) and electrically connected to the circuit layer ( 8 ), and a heat sink element, surface mounted on the substrate ( 6 ) separately from the LED package ( 7 ), the heat sink element having a body ( 2 ) of a heat conductive material surrounding the LED package ( 7 ), the body being thermally connected to the circuit layer ( 8 ), and being adapted to provide heat dissipation from the circuit layer ( 8 ) to a surrounding environment, wherein a surface ( 3 ) of the heat sink element facing the LED package is adapted to form part of a beam shaping optics for shaping light emitted from the LED package. Since the heat sink body is in thermal contact with the circuit layer, the heat resistance from the LED package to the heat sink body via the circuit layer is minimized.

The invention claimed is: 
     
       1. A light emitting device comprising:
 a substrate having an electrically conducting circuit layer, 
 a LED package surface mounted on said substrate and electrically connected to said circuit layer, wherein said LED package includes at least one terminal; and 
 a heat sink element, surface mounted on said substrate separately from said LED package, forming a surface mount between said heat sink element and said substrate, said heat sink element having a body of a heat conductive material surrounding said LED package, said body being thermally connected to said circuit layer, and being adapted to provide heat dissipation from said circuit layer to a surrounding environment, the at least one terminal extending to the surface mount between said heat sink element and said substrate, such that the heat sink element is connected to the at least one terminal; 
 wherein a surface of said heat sink element facing said LED package is adapted to form part of a beam shaping optics for shaping light emitted from said LED package and 
 a light sensor electrically connected to the beam shaping optics formed by the surface of the heat sink element, said light sensor being positioned to receive light emitted by the LED package; 
 wherein said heat sink element is electrically connected between at least two connection points, through said surface mount between said heat sink element and said substrate, to said circuit layer, such that said heat sink element forms part of an electrical circuit and conducts current, such the light sensor is powered by the current conducted by the heat sink element. 
 
     
     
       2. The light emitting device according to  claim 1 , wherein the body is a metal sheet folded to a cup-shape. 
     
     
       3. The light emitting device according to  claim 1 , wherein said body is made of a metal. 
     
     
       4. The light emitting device according to  claim 1 , wherein said body is made of at least partly transparent material. 
     
     
       5. The light emitting device according to  claim 1 , wherein said surface of said body facing said LED package is transparent, highly reflective, Lambertian reflective or specular. 
     
     
       6. The light emitting device according to  claim 1 , wherein said surface of said body facing said LED package is provided with a phosphorescent material adapted to convert the color of the LED radiation. 
     
     
       7. The light emitting device according to  claim 1 , wherein the heat sink element comprises two parts, each part being separated from the other part, each part thermally connected to said circuit layer. 
     
     
       8. The light emitting device according to  claim 1 , wherein the heat sink element is soldered to said circuit layer. 
     
     
       9. A method of assembling a light emitting device, said method comprises the steps of:
 providing a surface of a substrate with an electrically conducting circuit layer; 
 surface mounting a LED-package on said substrate, in electrical connection with said circuit layer, wherein said LED package includes at least one terminal; 
 surface mounting a separate heat sink element on said substrate, adjacent to said LED package, such that a surface mount between said heat sink element and said substrate is formed, and such that said heat sink element is brought into thermal connection with said circuit layer, so as to provide heat dissipation from said circuit layer to a surrounding environment, the at least one terminal extending to the surface mount between said heat sink element and said substrate, such that the heat sink element is connected to the at least one terminal; and 
 electrically connecting a light sensor solely to the beam shaping optics formed by the surface of the heat sink element, said light sensor being positioned to receive light emitted by said LED package; 
 wherein said heat sink element is electrically connected between at least two connection points, through said surface mount between said heat sink element and said substrate, to said circuit layer, such that said heat sink element forms part of an electrical circuit and conducts current, such that the light sensor is powered by the current conducted by the heat sink element.